Update July 30, 2017: a new simplified method that works for both Linux/MacOS and Windows with no changes to your Flask project required.

Visual Studio Code with the the Python extension makes for a great Python development environment – especially if you work on blended Python/Javascript web apps. Here’s how to debug a Flask 0.11.x (or later) app without having to add files or modify your project code. See “Solution 2” here for debugging an older version of Flask.